The present invention relates to an optical coupler (photointerrupter) that has an object passageway in an optical path from a light-emitting device to a light-receiving device and detects the presence or absence of an object or the passage of an object, a manufacturing method therefor and electronic equipment that employs the optical coupler.
Conventional optical couplers having connector terminals include an optical coupler (JP3176496) as shown in FIGS. 26A through 26C, an optical semiconductor device (H08-125218 A) as shown in FIG. 27 and a semiconductor optical coupler (H08-116085 A) as shown in FIG. 28.
Reference is first made to JP3176496. FIGS. 26A and 26B show states on the way of the manufacturing process of an optical coupler, and FIG. 26C shows a cross section of the finished product.
As shown in FIG. 26A, a lead frame 1, on which a light-emitting device (not shown) and a light-receiving device (not shown) are bonded, wired and molded with a translucent resin, is bent in an appropriate position, making the light-receiving device and the light-emitting device face each other. FIG. 26A further shows a light-emitting device mold resin 2 and a light-receiving device mold resin 3. In this case, by cutting one end (cradle) of the lead frame 1 by lead cutting in a bending step for bending the lead frame 1, connector terminals 4, 5, 6 are formed.
Next, as shown in FIG. 26B, the lead frame 1 and a connector 7 are connected together by spot welding of the connector terminals 4, 5, 6 of the lead frame 1 to pins 8 (see FIG. 26C) of the connector 7.
Finally, as shown in FIG. 26C, the lead frame 1 connected to the connector 7 is housed in an exterior casing 9, and a pin 10 made of a thermoplastic resin for fixation provided at a portion of the exterior casing 9 to be fit to the lead frame 1 is inserted into a hole (not shown) provided at the lead frame 1. On the other hand, by inserting a pin 11 made of a thermoplastic resin for fixation provided at a portion of the exterior casing 9 in the vicinity of the connector terminals 4, 5, 6 (only the connector terminal 4 is seen in FIG. 26C) of the lead frame 1 in between the connector terminals 4, 5, 6 and deforming by heat the pins 10, 11 made of the thermoplastic resin, the lead frame 1 and the exterior casing 9 are fixed together. Since the pins 10 and 11 are deformed by heat in FIG. 26C, the shapes of the pins before the deformation are not shown.
Next, JP H08-125218 A is described. As shown in FIG. 27, a board 23 on which a light-emitting device 21 and a light-receiving device 22 are mounted is housed in a housing 27 that has a trench portion 24 at the center and internally has reflecting surfaces 25 and 26 on both sides with interposition of the trench portion 24 with the mounting surface of the light-emitting device 21 facing upward. Then, a plurality of connector pins 28 for external connection are electrically connected to a terminal portion of the board 23 by, for example, soldering.
Next, JP H08-116085 A is described. As shown in FIG. 28, the semiconductor optical coupler is formed by inserting a light-emitting device 33 and a light-receiving device 34 from above into a connection part 32 formed by insert molding of a thin conductive plate having connector terminals 31 and a device socket portion with a plastic resin, attaching a casing 35 formed of a light-shielding resin to it and thereafter press fitting a connector housing 36 to the connector terminals 31. In this case, the connector housing 36 is selected according to the opposite side connector 37 to be connected.
However, the conventional optical coupler disclosed in JP3176496, the conventional optical semiconductor device disclosed in JP H08-125218 and the conventional semiconductor optical coupler disclosed in JP H08-116085 have the problems as follows.
That is, in the conventional optical coupler disclosed in JP3176496 and the conventional optical semiconductor device disclosed in JP H08-125218, a step (spot welding, soldering and the like) for connecting the connector to the lead frame (board) and a step (thermal caulking and the like) for joining the mutually connected connectors and the lead frame (board) to the exterior casing (housing) are necessary for the individual three parts constructed of the connector, the lead frame (board) and the exterior casing (housing). This therefore leads to the problems of a large parts count and many steps necessary for the assembling.
Moreover, in the conventional semiconductor optical coupler disclosed in JP H08-116085, the connector housing 36 is fixed by press fitting to the terminals 31 of the thin conductive plate. Accordingly, there is the problem that a whisker is generated from a portion to which a pressure is applied at the terminals 31 in the case of, for example, tin-plated terminals 31 and it is possible that an electrical shortcircuit occurs between the terminals 31 and between the terminals of the light-emitting device 33 and the light-receiving device 34.
There is a further problem that the opposite side connector 37 having a pitch of 2 mm cannot be inserted in, for example, a case where the terminals 31 have a pitch of 1.5 mm. Generally, there are numbers of kinds of connectors, and it is necessary to prepare semiconductor optical couplers by the number of different connectors, leading to problems in terms of inventory control and production control.